This application proposes a 5-year investigation designed to identify cognitive-behavioral mediating mechanisms related to the efficacy of a broad-spectrum, competence enhancement and drug abuse prevention intervention called Life Skills Training (LST). The proposed study will utilize data from a recently funded school-based drug abuse and violence project with inner-city minority students. The proposed study would expand the ongoing project by adding the assessment of cognitive-behavioral skills for a subsample of treatment and control students (n=500 per group). The LST intervention includes problem-specific material concerning drug abuse and violence prevention as well as generic cognitive-behavioral skills. New observational measures of cognitive-behavioral skills will be added to the existing battery of evaluation items. In addition to the observational study of 1,000 students, a substudy will be conducted on 200 adolescents selected from this group for a more in-depth analysis of family interactions and stress reactivity. The proposed study is divided into a 6-month developmental period, a 6-month pilot period, a 36-month intervention phase consisting of a large-scale randomized trial, and a 12-month data analysis/scientific dissemination phase. Forty New York City schools (N=4,000) would be randomly assigned to treatment and control conditions. The treatment condition would receive a drug abuse and violence prevention intervention consisting of school and parent intervention components. A secondary objective will be to assess the role of cognitive-behavioral skills acquisition in the development of adolescent drug use and aggressive/violent behavior among non-treated controls. A final objective is to increase our understanding of family interactions and physiological processes and their role in the etiology and prevention od drug abuse. The study is significant because it would not only offer the potential of demonstrating the effectiveness of a promising intervention on two important public heath problems, but would also provide the opportunity to investigate linkages between these important problem behaviors' and cognitive-behavioral skills hypothesized to be associated with both drug use and aggression/violence.